Diversity and Functional Diversity and Functional Variation of Denitrifying Variation of Denitrifying Bacterial Communities in the Bacterial Communities in the Cape Fear River EstuaryCape Fear River Estuary

Brian Shirey

Marine Biology

Project GoalsProject Goals

• Provide insight into denitrifying bacterial community structure

• Examine relationships between bacteria and their environment

• Provide answers to questions

What’s The Big Deal About What’s The Big Deal About Bacteria?Bacteria?The good

The bad

And the ugly

Salmonella typhimurium

Denitrifying BacteriaDenitrifying Bacteria

Anaerobic– Utilize nitrate during respiration

Comprise over 50 different genera

Ubiquitous

Ecological ImportanceEcological Importance

Vital role in global nitrogen cycle

Ecological Importance cont.Ecological Importance cont.

Contribution to global warming– Production of greenhouse gasses

NO3- NO2

- N2O NO N2

Nitrogen oxides

Ecological Importance cont.Ecological Importance cont.

Effective in bioremediation– Reduction of nitrate entering ground

and surface waters

Global SignificanceGlobal Significance

Understanding the mechanisms of denitrification is critical to our understanding of the global nitrogen cycle

Applied methodologies promote a healthy, balanced, captive ecosystem

Experimental DesignExperimental Design

Collect samples

Perform bacterial diversity and phylogenetic analysis

Perform community functionality analysis

Sediment SamplingSediment Sampling

Sediments collected from 5 sites along the cape fear river estuary

Measuring Bacterial DiversityMeasuring Bacterial Diversity

DNA sequencing– Isolation of functional genes encoding

for nitrate reductaseComparative analysis– Along environmental gradients

T-RFLP analysis– Profile of community structure

Measuring Functional DiversityMeasuring Functional Diversity

Incubation experiments– Designed to monitor denitrifying activity

Control

NaCl Nitrate

Anaerobic Enrichment Cultures

Research HypothesisResearch Hypothesis

Different components of a community will respond to different environmental inputs to maintain community functionality

Questions To Be AnsweredQuestions To Be Answered

Do denitrifying bacteria show the capability to readily adapt to sudden changes in their environment?

Is survivorship of denitrifying bacteria greatly reduced in sub optimal conditions?

To what degree do environmental conditions determine community structure?

ScheduleSchedule

Phase 1– Sequencing all DNA, setting up and

initialize incubation experiment Phase 2

– Completing incubation experiment and performing T-RFLP analysis

Phase 3– Analyze data, write paper

Jan. Feb. March April May June July Aug. Sep. Oct. Nov. Dec.

Phase 1

Phase 2

Phase 3

ConclusionConclusion

Denitrifying bacteria have a tremendous impact on the biosphere

Our biosphere is fueled by an underlying microbial world

The global community and the microbial community are eternally linked

Bacterial community as a window into past, present, and future

QUESTIONS?